1. Field of the Invention
The present invention concerns a detection unit for arrangement in a field generation unit of an MR apparatus, of the type wherein the detection unit has an RF transmission/reception system to transmit RF pulses and/or to receive MR signals, wherein the RF transmission/reception system surrounds a patient tunnel at a radial distance from a tunnel axis of the patient tunnel.
2. Description of the Prior Art
Such detection units are generally known.
MR systems, i.e. systems that detect magnetic resonance signals, normally have a detection unit of the type described above, in addition to a basic magnet and a gradient magnet system. The basic magnet generates a static, essentially homogeneous basic magnetic field in an examination volume. The gradient magnet system normally has multiple gradient coils. The basic magnetic field is momentarily varied in a spatially dependent manner by means of the gradient coils of the gradient magnet system. A spatial coding by means of the gradient coils ensues in the excitation of magnetic resonances, which are excited by RF pulses emitted by the RF transmission/reception system. Frequency and phase coding also ensue in the acquisition of the signals resulting from excited magnetic resonances.
The basic magnet, the gradient magnet system and the detection unit are normally concentrically arranged. The basic magnet tangentially extends around the tunnel axis, and extends over a relatively long section as viewed in the direction of the tunnel axis. The gradient magnet system is radially arranged within basic magnet. The radio-frequency transmission/reception system is radially arranged within the gradient system.
Due to the concentric arrangement of the individual components, the tunnel diameter of the patient opening is relatively small. In the prior art the diameter is even further limited by each additional component. This applies independent of whether the additional component is arranged radially within the radio-frequency transmission/reception system (also called a whole-body system in the following) or radially outside of the RF transmission/reception system. Examples of such additional components are special gradient coils (not always used), additional RF systems, PET detectors (positron emission tomography detectors) etc.